哪位能告诉下这段VHDL程序的错误
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity store is
port( q4,q3,q2,q1:in std_logic_vector(3 downto 0);
d3,d2,d1:out std_logic_vector(3 downto 0);
c,k:in std_logic;
ygreen,yred,alert:out std_logic);
end store;
architecture rtl of store is
signal x3,x2,x1:std_logic_vector(3 downto 0);
begin
process(k,q4,c)
begin
if k='0' then
ygreen<='1';
yred<='0';
x3<=q3;
x2<=q2;
x1<=q1;
if q4='1'then alert<='1';
end if;
else
ygreen<='0';
yred<='1';
x3<=q4;
x2<=q3;
x1<=q2;
if c='1' then
alert<='1';
end if;
end if;
d3<=x3;
d2<=x2;
d1<=x1;
end process;
end rtl;
当K=0时,为1∼999Hz量程档,